Today, dollar for dollar, is the 318 faster than the 340 ???

Ceedawg said
Well then I’ll turn my 340 5900 rpm. Both engines are capable of the same rpm since they have same crank. If bore size means nothing WHY do they notch the top of the bore around the valve? 22” less means a smaller pry bar to lift an object, nothing you can do to change that, WITH ALL THE OTHER PARTS BEING EQUAL.

Didn't say bore size means nothing and some notch it's not a necessary mod for a 318 most don't. It's just doesn't suck especially with a rebuild overbore it's not that far from the so called magical 4" bore, LS guy's make 400-500 NA hp with 4.8l and 5.3l with a 3.78" bore, there basically cid wise close to 273 and 318 and if these engines came factory with something like edelbrock heads.

And yes a 340 and 318 are capable to turn the same rpm and if took out to the limits 318 obviously be behind but the 340 would need more cylinder head than the 318 to do so. So if use same cam and heads on both engines the 340 should peak at a lower rpm than the 318 will probably some ratio constant with there displacements.

But if you take a 340 vs 416 since they have the same bore the 340 will alway be able to turn enough rpm higher than the 416 to theoretically make up the displacement difference.

But were not talking about taking out to the limits here, I'd bet most street 340 peak somewhere between 5000-6000 rpm, so a 318 will need to peak 5350-6420 rpm about 7% higher to keep up and little more to beat. Not like the 318 gonna need radically different cam and heads to do so. But obviously there's more to it like Volumetric efficiency percentage VE%, and good way to know that is torque to cid ratio most engine will fall somewhere between 1-1.45:1 lbs-ft:cid. Most street guys are gonna make between 1.15-1.25:1 since there's a 9% difference which is more than the cid diffence there's a chance a well put together 318 can make as much or slightly more torque than the 340 but not usually, a 318 may or not need slightly different cam and heads for best VE%, a 318 will need more gear and stall though.